Bees work to improve cotton yields

Doreen Muzzi Farm Press Editorial Staff | Dec 05, 2001

Placing a few honey bee colonies along the edges of your cotton fields may increase the amount of lint that finds its way into your picker come harvest time, according to a recent study at Alabama A&M University.

Entomologist Kenneth Ward says that in the past it was difficult to introduce pollinating insects into cotton fields due to the heavy pesticide usage required for cotton production.

However, the increase in recent years to insect-resistant cotton crops and the adoption of boll weevil eradication programs have decreased the number of insecticide applications growers need to make, providing a better opportunity for honey bees to help work their magic.

Could the introduction of supplemental honey bees into a field planted in an insect-resistant transgenic cotton variety, increase cotton fiber yield potential? The short answer, Ward says, is yes.

A two-year on-farm study undertaken by entomologists at Alabama A&M University appears to show an increase in the amount of fiber produced per cotton boll.

“What we found the first year was that the per-boll yield went down significantly as you got further away from the bees,” Ward says. “The second year we saw the same thing. And, although the yield findings still were significant, they weren't quite to the same degree as they were the first year of the study.”

According to Ward's data, in the study's first year, the bee field yielded 1,184 pounds per acre, and the non-bee field yielded 1,046 pounds per acre.

The next year, the bee field yielded 1,313 pounds per acre and the non-bee field yielded 1,212 pounds per acre.

“These trends were detected in producer fields, with limited control over experimental conditions,” he says. “The multi-year data from this study was consistent, and it suggests a positive impact of supplemental honey bees on cotton yield indicators in Bt cotton.”

In the first year of the study, the bee colonies were placed in adjacent corners of one 140- to 160-acre cotton field with another similarly sized field without bee hives used as a control field. Both fields were irrigated using a center pivot system and both were planted in Bt cotton. The bee field was supplemented with approximately one hive of honey bees per acre of cotton.

The study was repeated the next year by simply switching the hives of honey bees to the same positions in the opposite “control” field.

In both years, the bee fields and the non-bee fields were sampled in multiple field locations to obtain cotton yield data and bee activity data.

To break down the cotton yield components, 20 one-to-two-day-old flowering cotton blooms were tagged per sample point weekly for four weeks. The resulting bolls were also collected and counted later in the season, after a defoliation treatment.

To obtain estimates of bee activity in the fields, the researchers at Alabama A&M counted the number of foraging bees within a 40-foot radius for a period of three minutes per sampling point.

The bee activity in the cotton field was as would be expected, Ward says.

“Once you got halfway into the field the bee activity fell off to the level in the non-bee field. There were still bees in both fields, but at different levels.

“This is a small study, but we feel it is reason enough to justify a larger study,” he says.

“The research results strongly suggest that the introduction of honey bees into a Bt cotton crop can have a positive impact on yield potential.”

An added benefit the Alabama researchers discovered was the successful production of honey in the hives along the cotton fields. The bee hives placed alongside the fields each yielded about 50 pounds of “very smooth” honey.